The present disclosure relates to an image processing apparatus for processing a digital image, and a method of processing a digital image.
Signal processing for the object of changing visibility of the image, such as white balance processing, black level adjustment, gamma correction, and KNEE correction of a digital image is generally performed for unprocessed image data obtained by image pickup.
For example, in Japanese Patent Application Laid-open No. 2009-033385 referred to as Patent Document 1, a technology relating to white balance adjustment for raw image data denoting unprocessed image data is described.
On the other hand, recently, digital high-definition broadcasting has been rapidly spread with the transition to terrestrial digital broadcasting. The high-definition data is now prescribed as image being 1920 pixels by 1080 pixels. However, it is predicted that the image resolution is further heightened in the future by super high resolution high-definition image such as 4K image being approximately 4000 pixels by 2000 pixels or 8K image being approximately 8000 pixels by 4000 pixels.
When the image resolution is heightened, the total amount of calculation for signal processing such as white balance processing, black level adjustment, gamma correction and KNEE correction becomes large. Therefore, the processing time is increased, and the electric power consumed in an apparatus performing the arithmetic processing is increased.
Further, in Japanese Patent Application Laid-open No. Hei 07-129769 (paragraph [0005]) referred to as Patent Document 2, a method of detecting a point having a significant change in an image as a characteristic point is described. For example, an analyzed value is calculated by analyzing a characteristic point of a signal having correlation between signals adjacent to each other so as to extract the point, a maximum value of the analyzed value is detected, a predetermined value corresponding to the maximum value is calculated as a threshold value, the threshold value and the analyzed value are compared with each other, and the analyzed value equal to or more than the threshold value is detected as a characteristic point. For the analysis, differential processing of a signal is adopted. However, in the Patent Document 2, neither the technology that signal processing for an image detected as a characteristic point is performed nor the technology that the result of the signal processing is set as an interpolated value and a value of at least one pixel other than the characteristic point is rewritten to the interpolated value is described.